Prospective Cohort Study Evaluating a Thermal Spa Programme in Symptomatic Knee Osteoarthritis

Inclusion Criteria: * Adults aged 50 years or older * Diagnosis of knee osteoarthritis affecting at least one knee, with radiographic Kellgren-Lawrence grade ≥ 2 confirmed by an X-ray performed within the past 3 years * Average knee pain intensity \> 30 mm on a 100-mm Visual Analog Scale (VAS) during the month prior to inclusion * Participants scheduled to undergo a 3-week thermal spa treatment at the Balaruc-les-Bains thermal center Exclusion Criteria: * Use of systemic or injectable corticosteroids within 1 month prior to inclusion * Intra-articular injection of hyaluronic acid or platelet-rich plasma (PRP) within the 3 months prior to inclusion * Active inflammatory joint disease (e.g., rheumatoid arthritis, spondyloarthritis, or crystal-induced arthropathies) * Current major depressive episode or psychotic disorders * Thermal spa treatment within the previous 6 months * Inability to read or write * Inability to complete follow-up for the entire study period (e.g., planned relocation, travel, professional commitments, or residence located more than 100 km from the study site) * Lack of informed consent * Pregnant or breastfeeding women * Individuals under legal protection (guardianship or curatorship) * Not affiliated with a national health insurance system * Individuals under judicial protection (safeguard of justice) * Participation in another clinical study with an ongoing exclusion period